Authors: Costa, JS; Rocha, AD; Correia, RA; Alves, JA
Author Full Name: Costa, Joana S.; Rocha, Afonso D.; Correia, Ricardo A.; Alves, Jose A.
Título: Developing and validating a nestling photographic aging guide for cavity-nesting birds: an example with the European Bee-eater (Merops apiaster)